At the highest level, this patent application presents the concept of retrofitting existing buildings with new windows such as optically switchable windows. In various embodiments, an existing building is retrofit with optically switchable window having a controller for controlling the switching of the optical state of the window.
There are a number of reasons that it may be desirable to retrofit new windows into an existing building. The new windows may provide better energy management, be more aesthetically pleasing, and/or provide additional functionality compared to the pre-existing windows. Also, retrofitting is generally more cost effective than window replacement and can be accomplished one window at a time with limited disruption to occupants of the building.
The design of windows on a building can strongly influence the amount of energy used by that building. For instance, heat loss through windows in the winter can result in substantial energy wasted keeping the building warm, and heat gain through windows in the summer can result in substantial energy being used to keep the building cool. Newer windows tend to have much better heat management performance than older windows. For instance, newer windows may have additional panes, additional coatings for blocking or reflecting certain types of radiation, an inner volume of inert gas or vacuum to reduce heat exchange, etc. These improvements, among others, make it particularly desirable to retrofit old windows.